技術標籤：mysql

一、左外連線

SELECT * FROM A LEFT JOIN B ON A.KEY = B.KEY

二、右外連線

SELECT * FROM A RIGHT JOIN B ON A.KEY = B.KEY

三、內連線

SELECT * FROM A INNER JOIN B ON A.KEY = B.KEY

四、左連線

SELECT * FROM A LEFT JOIN B ON A.KEY = B.KEY WHERE B.KEY IS NULL

五、右連線

SELECT * FROM A RIGHT JOIN B ON A.KEY = B.KEY WHERE A.
 
KEY IS NULL

六、全連線

• Mysql不支援下列方式

SELECT * FROM A FULL OUTER JOIN B ON A.KEY = B.KEY 

• Mysql支援下列方式

　SELECT * FROM A LEFT JOIN B ON A.KEY=B.KEY
　UNION
　SELECT * FROM A RIGHT JOIN B ON A.KEY=B.KEY

七、全外連線

• mysql不支援下列方式

SELECT * FROM A FULL OUTER JOIN B ON A.KEY = B.KEY WHERE A.KEY IS NULL OR B.KEY IS NULL
 

• mysql支援下列方式

　SELECT * FROM A LEFT JOIN B ON A.KEY=B.KEY WHERE B.KEY IS NULL
　UNION
　SELECT * FROM A RIGHT JOIN B ON A.KEY=B.KEY WHERE A.KEY IS NULL